1. Field of the Invention
The present invention relates to an acceleration sensor.
2. Description of the Related Art
Conventionally, there has been known an acceleration sensor in which an acceleration sensor element and a frame portion surrounding the element are deposited on a semiconductor substrate and the element is sealed off by bonding a cap to the frame portion, as disclosed in, for example, U.S. Pat. No. 6,441,450.
However, since both the acceleration sensor element and the frame portion are formed on the semiconductor substrate, if a crack is generated at a junction region between the cap and frame portion due to an external force or there is a residual stress at the junction region due to the difference in thermal expansion coefficient between the cap and the frame portion made of different materials, such crack or stress may easily advance or propagate and reach the acceleration sensor element. This may cause the characteristic of the acceleration sensor to change.